Performance of a showcase refrigeration system with multi-evaporator during on–off cycling and hot-gas bypass defrost

Cho, Honghyun; Kim, Yongchan; Jang, Inkyu

doi:10.1016/j.energy.2004.11.006

Cited by 61 publications

(15 citation statements)

References 7 publications

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“…5 For the defrosting method of a showcase refrigerating system with three evaporators, the on/off and hot gas bypass methods were compared, revealing that the latter displays greater refrigerating capacity and smaller temperature deviation than the former. 6 As described above, the hot gas bypass method is employed in conventional cooling cycles to control their capacity or to defrost evaporators or outdoor units, aiming at refrigerating capacity control, reducing temperature deviation, and/or saving energy.…”

Section: Theoretical Background To the Gas Bypass Cooling Cyclementioning

confidence: 99%

Improvement of temperature accuracy in oil cooler systems with gas bypass

Lee¹,

Yeom²,

Lee

2011

Int. J. Precis. Eng. Manuf.

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In keeping with the development of machine tools with higher speed, more axes, and a greater degree of sophistication, thermal deformation is becoming an important factor in the precision of machine tools. It has been found that thermal error accounts for about 70% of the total error in machine tools. As such, oil coolers which absorb heat from heat generating parts with cold oil are being used to reduce the error caused by thermal deformation. The gas bypass type oil coolers used in ultra-precision (temperature accuracy within ±0.1℃) machine tools are simple in structure and precise in terms of their temperature control performance; however, they have a limitation as regards temperature control due to the instability of their performance under light load conditions. In this study, an oil cooler system equipped with dual electronic valves was developed to solve the problems of the single electronic valve system and achieve more precise temperature control. To verify the performance of the developed system, its performance under the operating conditions of rated load, DIN 8602 standard, and ISO/DIS 230-3 operational mode was compared and analyzed. The proposed oil cooler system is applicable to semiconductor equipment, ultra-precision injection molds, and ultra-precision machine tools, and improves the quality of the products.

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Section: Theoretical Background To the Gas Bypass Cooling Cyclementioning

confidence: 99%

Improvement of temperature accuracy in oil cooler systems with gas bypass

Lee¹,

Yeom²,

Lee

2011

Int. J. Precis. Eng. Manuf.

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show abstract

“…To solve these deficiencies, researchers put forward some improvement measures or defrosting methods. Hot-gas bypass defrosting [8], which runs the compressor exhaust into the evaporator to melt the frost layer, successfully avoids the four-way valve switching in reverse-cycle defrosting. Fu et al [9] divided the out heat exchanger into two parts by a capillary tube, which were respectively used as the evaporator and condenser during the defrost process, and the experimental results indicated that the fluctuation of the discharge and suction pressures during the defrost process was much less than that in reverse-cycle defrosting.…”

Section: Introductionmentioning

confidence: 98%

Preliminary study of a novel defrosting method for air source heat pumps based on superhydrophobic fin

Wang

Liang

Yang

et al. 2015

Applied Thermal Engineering

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“…A comparative study was also presented with different by-pass schemes in terms of the system coefficient of performance (COP) and operating temperatures. Furthermore, Cho et al [7] investigated the performance of showcase refrigeration system and conducted experimental tests during on-off cycling and hot-gas defrosting. The investigation also revealed that the hot-gas by-pass method has higher refrigeration capacity and less temperature fluctuation than on-off cycling even though the former required more power consumption for running the compressor.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of a process cooling system retrofitted with HFC-404A refrigerant for precise manufacturing application

et al. 2011

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Precise-manufacturing facilities, which emphasize accurate and stable machining of the working components to be used in semiconductor industry, cannot function properly without appropriate and precise cooling. HCFC (hydro-chloro-floro-carbon) has been commonly used as the coolant for precise manufacturing facilities; but it is facing the pressing schedule to be phased out. Additionally, the dramatic variation of heat load during high-accuracy and high-speed applications need a critical control of coolant (brine or water) temperature. Use of eco-friendly HFC 404A to replace HFC has been suggested as an effective alternative to alleviate the problems. In this study, the performance of a process cooling system retrofitted with HFC-404A refrigerant was evaluated; the energy efficiency ratio and accuracy of temperature control specific to -15 o C precise manufacturing application were examined. Effects of using thermostatic expansion valve associated with hot-gas by-pass control scheme under different loading conditions have been investigated extensively. The energy efficiency ratio and accuracy of temperature control for the cooling system were measured and analyzed for comparing and evaluating HCFC-22 and HFC-404A using different throttling devices under specific coolant temperatures. The comprehensive studies on improving the accuracy of temperature control and energy-saving efficiencies through different temperature control strategies are presented in this paper.

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Performance of a showcase refrigeration system with multi-evaporator during on–off cycling and hot-gas bypass defrost

Cited by 61 publications

References 7 publications

Improvement of temperature accuracy in oil cooler systems with gas bypass

Improvement of temperature accuracy in oil cooler systems with gas bypass

Preliminary study of a novel defrosting method for air source heat pumps based on superhydrophobic fin

Experimental investigation of a process cooling system retrofitted with HFC-404A refrigerant for precise manufacturing application

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